1. Field of the Invention
The present invention relates to the field of display techniques, and in particular to a manufacturing method of flexible TFT substrate.
2. The Related Arts
In the field of display technology, the panel display technology has replaced cathode ray tube (CRT) display. Because of the advantages of high display quality, low power-consumption, thinness and wide applications, the e panel display device has been widely used in mobile phones, TV, PDA, digital camera, notebook PC, desktop PC, and other consumer electronic products, and becomes the mainstream of the display device.
The thin film transistor (TFT) is the main driving element used in the liquid crystal display (LCD) and active matrix organic light-emitting diode (AMOLED) display device, and is directly related to future progress of the high-performance panel display device.
The TFT includes various structures, as well as various materials for manufacturing the active layer of TFT of corresponding structure. Among the options, the low temperature poly-silicon (LTPS) material is one of the preferred options. Due to the regular atomic arrangement of LTPS, the carrier migration rate is high. For voltage-driven LCD display devices, the smaller-sized TFT can be used to realize the LTPS TFT to achieve deflection driving on the liquid crystal (LC) molecules because of the high migration rate of LTPS TFT, which greatly reduces the volume of the TFT, increase light transmission area, obtain higher brightness and resolution. For the current-driven AMOLED display device, the LTPS TFT can better meet the drive current requirements, and can be applied to flexible organic light-emitting diode (OLED) substrate, and arouse widespread attention in recent years.
In the TFT substrate, the gate of the TFT is located on the same layer as the gate line to form a first metal layer, the source and the drain of the TFT and the data line are located on the same layer to form a second metal layer. An interlayer dielectric (ILD) layer must be provided between the first metal layer and the second metal layer as an insulating layer for isolating the first metal layer from the second metal layer. At present, in conventional flexible TFT substrates, the ILD layer is typically a two-layer inorganic film layer comprising a silicon oxide (SiOx) layer and a silicon nitride (SiNx) layer. However, in recent years, flexible TFT technology is becoming more and more demanding, so the conventional laminated inorganic film ILD material is difficult to meet the requirements of flexible substrate.